Apparatus for producing activated carbon



Jan. 2,= 1951 K. B. STUART 2,536,106

APPARATUS FOR PRODUCING ACTIVATED CARBON Filed March 4, 1948 2.9 Zffi 27 INVENTOR KENNETH MRTMJTUART ATTO RNEYS Patented Jan. 2, 1951 APPARATUS FOR PRODUCING ACTIVATED CARBON Kenneth B. Stuart, Denver, 0010., assignor to The Colorado Fuel 8; Iron Corporation, a corporation of Colorado Application March 4, 1948, Serial No. 12.966

12 Claims.

This invention relates to apparatus for producing activated carbon and has for its object certain improvements in such apparatus for producing activated carbon of uniform high quality.

In the production of activated carbon, it is customary first to char or carbonize suitable raw carbonaceous material and then to activate it, usually with a hot mildly oxidizing gas, such as superheated steam. To this end, the activating as is passed into a column of previously charred carbonaceous material. The gas tends to channel its way through the column of char, following the line of least resistance, with the result that the char is not uniformly activated. In addition, the gas tends to carry away suspended fines to an objectionable extent.

Investigations confirm my discovery that an apparatus may be employed in which the carbonaceous material may be successively carbonized and activated, the structural elements of the apparatus being so arranged as to assume substantially uniform distribution of the carbonizin and activating gases among the solid particles of carbonaceous material. In this way each carbon particle receives substantially the same treatment. The carrying away of fines is also prevented.

In accordance with the invention, the apparatus comprises an upright retort with an inlet at the top for ingress of carbonaceous material and an outlet at the bottom for egress of activated carbon, the retort being divided into an upper carbonizing chamber and a lower activating chamber. A manifold with a top wall and a bottom wall is disposed laterally between the two chambers. An inlet extends through the wall of the retort and connects the manifold for the passage of activating gas into the manifold. A plurality of spaced upright conduits extend completely through the manifold for the passage of char from the upper chamber to the lower chamber, the ends of the conduits terminating at the top and bottom walls of the manifold to assure easy access of practically all of the char in the upper chamber to the conduits. A plurality of spaced and perforated down-pipes depend from the bottom wall of the manifold deeply into the lower chamber for the passage of gas from the manifold to the lower chamber. A plurality of spaced riser pipes extend completely through the manifold, the lower portions of the pipes depending downwardly well into the lower chamber and the upper portions of the pipes extending upwardly well into the upper chamber, the lower portions and the upper portions of the pipes being perforated so that gas in the lower chamber may pass into the lower portions and be discharged through the upper portions into the upper chamber.

The upper end of the retort is advantageously provided with an automatic pressure controlled valve outlet for the controlled escape of exhaust gases from the upper chamber. The manifold preferably extends completely across the retort, thus forming the bottom of the upper chamber and the top of the lower chamber.

So that the carbonizing and activating steps may be conducted under pressure, the inlet at the top of the retort communicates with a charge chamber, a valve being disposed between the charge chamber and the inlet to open and close the passageway between the two. With an arrangement such as this, the valve may be opened to permit the passage of a charge of the raw carbonaceous material into the retort, after which the valve may be closed to prevent the escape of exhaust gases by way of the charge chamber. Exhaust gases are preferably bled from the retort through the automatic pressure controlled valve outlet at the upper end of the retort.

The outlet at the bottom of the retort communicates with a cooling chamber, a valve being disposed between the outlet andthe cooling chamber to open and close the passageway between the two. A star discharge is preferably located at the outlet to transfer activated carbon from the retort to the cooling chamber. With the valve closed, pressure conditions may be maintained within the retort. From time to time, the valve may be opened and the star discharge operated to transfer activated carbon from the retort to the cooling chamber, after which the valve is again closed to restore the desired pressure conditions within the retort.

These and other features of the invention will be better understood by referring to the accompanying drawing, taken in conjunction with the following description, in which Fig. l diagrammatically shows an apparatus illustrative of a practice of the invention and Fig. 2 is a section on the line 2-2 of Fig. 1.

The apparatus shown comprises a retort i0 having a heavy outer insulating shell ii. The retort stands in upright or vertical position and is cylindrical in plan with a frusto-conical upper section I! and an inverted frusto-conical lower section I3. The retort is divided into an upper or carbonizing chamber [4 and a lower or activating chamber I5. A manifold I6 with a top wall 3 .r I! and a bottom wall 18 is disposed horizontally and fills the space between the two chambers. An inlet 19 extends through the wall of the retort and connects the manifold for the passage of activating gas into the manifold. A plurality of short and spaced conduits 20 extend completely through the manifold for the passage of char from the upper chamber to the lower chamber, the ends of the conduits terminating at the top and bottom walls of the manifold to assure easy access of practically all of the char in the upper chamber to the conduits. A plurality of spaced and perforated down-pipes 2| depend from the bottom wall of the manifold deeply into the lower chamber for the passage of gas from the manifold to the lower chamber. The number of down-pipes and perforations are such as to assure a substantially even distribution of the activating gas in the body of char undergoing activation in the lower chamber. A plurality of spaced riser pipes 22 extend completely through the manifold, the lower portion of the pipes depending downwardly well into the lower chamber and the upper portions of the pipes extending upwardly well into the upper chamber, the lower portions and the upper portions of the pipes being perforated so that gas in the lower chamber may pass into the lower portions of the pipes and be discharged from the upper portions of the pipes into the upper chamber. Here again, the number of pipes and their perforations are such as to assure a substantially even withdrawal of exhaust gases from the char undergoing activation in the lower chamber into the lower portions of the riser pipes and a substantially even distribution of the exhaust gases in the carbon undergoing charring or carbonization in the upper chamber.

An automatic pressure controlled valve outlet 25 extends through the upper frusto-co'm'cal section of the retort to the exterior for the controlled escape of exhaust gases from the upper chamber. The outlet is preferably located above the normal carbon level of the upper chamber so as to facilitate withdrawal of the exhaust gases.

The upper frusto-conical section of the retort terminates in an inlet 26 which connects with a charge chamber 21 and a measuring bin 28, a valve 29 being interposed between the measuring bin and the charge bin and a similar valve 30 being disposed between the charge chamber and the inlet of the retort.

The lower frusto-conical section of the retort terminates in an outlet 33 which connects with a charge chamber 34 fitted with an openable closure 35. In the specific construction shown, a star discharge 36 is associated with the outlet of the retort to facilitate removal of activated carbon therefrom. A valve 31 is interposed between the star discharge and the charge chamber.

The apparatus may be employed as follows in carbonizing and activating suitable carbonaceous material:

Hot activating gas is passed through inlet l9 into manifold l6, downwardly into and then out of perforated down-pipes 2|, into lower chamber l5, into the lower portions of perforated riser pipes 22, out of the upper portions of perforated riser pipes 22, into upper chamber l4. Some of the hot gas also passes from lower chamber I5 through conduits 20 into upper chamber H. The gas accumulating in the upper chamber is suitably bled therefrom through valved'outlet 25. Sufiicient hot activating gas is thus passed into and through the retort to bring it to and maintain it at a predetermined and optimum operating temperature.

The retort is filled with suitable raw carbonaceous material, such as finely-divided an- 5 thracite coal. Valves 29 and 30 are opened and valve 31 and closure are closed. The coal is then passed through measuring bin 28 and charge chamber 21 into retort In. As the coal tends to accumulate in upper chamber l4, some of it passes through conduits 20 until lower chamber [5 is filled. Coal is passed into the re tort in this manner until upper chamber I4 is also substantially filled. Valves 29 and 30 are then closed.

The feeding of hot gases into the system as described above is continued in order suitably to treat the coal. It will be clear that as the activating gas escapes from perforated down-pipes 2|, it is substantially evenly distributed among the particles of coal inlower chamber l5. The partially spent gas passes through interstices between adjoining particles until it enters the perforations of the lower portions of riser pipes 22 depending in the lower chamber. The gas thus entering the riser pipes rises upwardly to' the upper portions of the pipes from which it escapes and is substantially evenly distributed among the particles of coal in upper chamber it. Some of the partially spent gas also rises upwardly through conduits 20 filled with coal particles. This, of course, aids in the even distribution of the gas throughout the body of coal in the upper chamber. Exhaust gas accumulating under upper frusto-conical section I2 of the retort is bled off through valved outlet 25 under controlled pressure conditions.

After a suitable interval, valve 31 is opened and star discharge 36 is set in operation to transfer treated coal from lower chamber [5 to cooling chamber 34. Valve 31 is then closed and closure 35 opened or removed after a suitable cooling period to withdraw the treated coal; after which the closure is closed or returned.

To replace coal or carbon thus removed from the system, additional coal is passed into measuring bin 28. With valve 30 still closed, valve 29 is opened and the coal transferred from bin 28 to charge chamber 21. Valve 29 is then closed and valve 30 is opened to pass the coal from charge 5 chamber 21 to upper chamber [4 of the retort;

after which valve 30 is again closed.

As a batch of activated carbon is removed from the lower chamber, an equal volume of charred coal drops from upper chamber l4 through conduits 20 into the lower chamber. A batch of raw coal is then fed to the upper chamber to replace that thus removed. In this way successive batches of material are passed through the retort by gravity as it is successively charred and activated.

Activating gases of various kinds may be employed. The most common are steam and carbon dioxide, or both. Activating gas may be obtained, for example, by burning combustible gas under pressure in air. The activating step is conducted under positive pressure, that is, superatmospheric pressure. This may vary over a rather wide range but should be substantial, preferably in excess of 5 pounds per square inch gauge pressure. I have had excellent results with pressures in the neighborhood of 20 pounds per square inch gauge pressure. The pressure must, however, be consistent with safety, depending upon the strength of the apparatus.

Similarly, carbonizing gases of various kinds 76 may be employed. It is economical to use the a gases from the activating step for the carbonizing step, as described. It is also preferable to conduct the carbonizing step under a substantial positive pressure, say of the same order as in the activating step.

The flow of activating and carbonizing gases through the lower and upper chambers should be substantial and may of course vary overa rather wide range. I have, for example, passed activating gas in'contact with the char at a temperature of about 1400 F, to about 1600 F. and at a rate of about 100 to 240 standard cubic feet of gas per hour per 1 to 2 pounds of activated carbon produced from the char; and carbonizing gas in contact with the carbon (Colorado subbituminous coal) at-the rate of about 2500 to 6000 standard cubic feet of gas per 25 to 50 pounds of char per hour. Activation and carbonization of the carbon may be effected in a number of ways, such for example, as described in my copending application Serial No. 501,044, filed September 3, 1943 now Patent Number 2,501,700.

It will be clear to those skilled in this art that the practice of the invention lends itself to various modifications. While theapparatus is particularly useful in the production of activated carbon, it may be used for other purposes; more especially in the treatment of finely divided material with a gas, in which the gas is passed through the material and there is a tendency for suspended fines to be carried from the material by the gas.

This is the case, for example, in the exfoliation of vermiculite. When treated with heating gases under ordinary conditions, the problem of excessive product loss is twofold. In addition to fines, the large decrease in specific gravity on expansion makes treatment by direct contact with moving gases impractical because of an excessive loss of product in the exit gases. With apparatus of the present invention, however, these disadvantages may be largely overcome. Crushed vermiculite is placed therein and treated essentially as described above. Such fines as are produced are precipitated in the low velocity sections so that the exit gases are substantially free of fines.

Similar difficulties are encountered in theexpansion or popping of perlite. They may be overcome when the perlite is treated like the vermiculite in accordance with the invention.

The section or sections of the apparatus specially provided to induce low velocity of the gases is particularly useful in any furance and the like used for the treatment or dryingof a relatively finely divided product in direct contact with moving gases. Such fines as are produced are precipitated from the stream of gases in the low velocity section, so that the gases may exit from the apparatus substantially free of fines.

'I claim:

1. In apparatus for producing activated carbon, the improvement comprising an upright retort with an inlet at the top for ingress of carbonaceous material and an outlet at the bottom for egress of activated carbon, the retort being divided into an upper carbonizing chamber and a lower activating chamber, a manifold with "a top wall and a bottom wall disposed laterally between the two chambers, an inlet extending through the wall of the retort and connecting the manifold for the passage of activating gas into the manifold, a plurality of spaced upright conduits extending completely through the manifold for the passage of char from the upper chamber to the lower chamber, the ends of the conduits terminating at the top and bottom walls of the manifold to assure easy access of practically all of the char in the upper chamber to the conduits, a plurality of spaced and perforated down-pipes depending from the bottom wall of the manifold deeply into the lower chamber for the passage of a gas from the manifold to the lower chamber, a plurality of spaced riser pipes extending completely through the manifold, the lower portions of the pipes depending downwardly well into the lower chamber and the upper portions of the pipes extending upwardly well into the upper chamber, the lower portions and the upper portions of the pipes being perforated so that gas in the lower chamber may pass into the lower portions and be discharged through the upper portions into the upper chamber.

2. Apparatus according to claim 1, in which the upper end of the retort is provided with an outlet for the escape of exhaust gases from the upper chamber.

3. Apparatus according to claim 1, in which the manifold extends completely across the retort thus forming the bottom of the upper chamber and the top of the lower chamber.

4. Apparatus according to claim 1, in which the inlet at the top of the retort communicates with a charge chamber, a valve being disposed between the charge chamber and the inlet to,

open and close the passageway between the two.

5. Apparatus according to claim 1, in which the inlet at the top of the retort communicates with a charge chamber, a valve being disposed between the charge chamber and the inlet to open and close the passageway between the two, and a valve at the inlet to the charge chamber adapted to be opened to admit a charge of carbon to the charge chamber and to be closed after the charge is passed into the charge chamber.

6. Apparatus according to claim 1, in which the outlet at .the bottom of the retort communicates with a cooling chamber, a valve being disposed between the outlet and the cooling chamber to open and close the passageway between the two.

7. Apparatus according to claim 1, in which the inlet at the top of the retort communicates with a charge chamber, a valve being disposed between the charge chamber and the inlet to open and close the passageway between the two, and the outlet at the bottom of the retort communicates with a cooling chamber, a valve being disposed between the outlet and the cooling chamber to open and close the passageway between the two.

8. Apparatus according to claim 1, in which the inlet at the top of the retort communicates with a charge chamber, a valve being disposed between the charge chamber and the inlet to 'open and close the passageway between the two, a valve at the inlet to the charge chamber adapted to be opened to admit a charge of carbonaceous material to the charge chamber and to be closed after the chargeis passed into the charge chamber, and the outlet at the bottom of the retort communicates with a cooling chamber, a valve being disposed between the outlet and the cooling chamber to open and close the passageway between the two.

9. Apparatus according to claim 1, in which the outlet at the bottom of the retort communicates with a cooling chamber, a star discharge being disposed between the outlet and the cooling chamber to transfer activated carbon fro the outlet to the cooling chamber.

10. Apparatus according to claim 1, in which the outlet at the bottom of the retort communicates with a cooling chamber, a star discharge and a valve being disposed, respectively, between the outlet and the cooling chamber to transfer activated carbon from the outlet to the cooling chamber and to open and close the passageway between the two.

11. Apparatus according to claim 1, in which the inlet at the top of the retort communicates with a charge chamber, a valve being disposed between the charge chamber and the inlet to open and close the passageway between the two, and the outlet at the bottom of the retort communicates with a cooling chamber, a star discharge being disposed between the outlet and the cooling chamber to transfer activated carbon fromfghe outlet to the cooling chamber.

12. Apparatus according to claim 1, in which the inlet at the top of the retort communicates with a charge chamber, a valve being disposed between the charge chamber and the inlet to open and close the passageway between the two,

and the outlet at the bottom 01' the retort communicates with a cooling chamber, a. star discharge and a valve being disposed. respectively, between the outlet and the cooling chamber to transfer activated carbon from the outlet to the cooling chamber and to open and close the passageway between the two.

KENNETH B. STUART.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,536,106 January 2, 1951 KENNETH B. STUART It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 1, lines 21 and 22, for the word assume read assure; column 8, line 21, for the patent number 2,343,862 read 2,3423%;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 6th day of March, A. D. 1951.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

1. IN APPARATUS FOR PRODUCING ACTIVATED CARBON, THE IMPROVEMENT COMPRISING AN UPRIGHT RETORT WITH AN INLET AT THE TOP FOR INGRESS OF CARBONACEOUS MATERIAL AND AN OUTLET AT THE BOTTOM FOR EGRESS OF ACTIVATED CARBON, THE RETORT BEING DIVIDED INTO AN UPPER CARBONIZING CHAMBER AND A LOWER ACTIVATING CHAMBER, A MANIFOLD WITH A TOP WALL AND A BOTTOM WALL DISPOSED LATERALLY BETWEEN THE TWO CHAMBERS, AN INLET EXTENDING THROUGH THE WALL OF THE RETORT AND CONNECTING THE MANIFOLD FOR THE PASSAGE OF ACTIVATING GAS INTO THE MANIFOLD, A PLURALITY OF SPACED UPRIGHT CONDUITS EXTENDING COMPLETELY THROUGH THE MANIFOLD FOR THE PASSAGE OF CHAR FROM THE UPPER CHAMBER TO THE LOWER CHAMBER, THE ENDS OF THE CONDUITS TERMINATING AT THE TOP AND BOTTOM WALLS OF THE MANIFOLD TO ASSURE EASY ACCESS OF PRACTICALLY ALL OF THE CHAR IN THE UPPER CHAMBER TO THE CONDUITS, 